The present disclosure generally relates to a device, system and method for minimizing environmental fluctuations around a corrosion sensor to overcome the variation commonly encountered in corrosion rate measurements and assess the true contamination level in data centers.
Corrosion is determined by the synergistic effects of “air” parameters such as temperature, humidity, air flow (speed), and gaseous contamination concentrations. Any of the above mentioned “air” parameters will affect the corrosion rate of certain metals, and as a result, measurement of the corrosion rate can vary depending on the location of the measurement and the environment that a corrosion sensor will see.
For example, corrosion sensors positioned at the outlet of an air conditioning unit may not detect the full extent of corrosion as the temperature is too low to trigger the corrosion, but at higher temperature a finite corrosion rate may be detected. Depending on the measurement location, either no corrosion or significant corrosion could be measured in the same facility.
Air parameters like temperature, humidity and air flow can influence corrosion in polluted atmospheres resulting in corrosion rates that can differ by more than a factor of five (5) or larger in the same facility.
The proliferation and spread of facilities such as information technology (IT) Data Centers (DC) into geographies with higher levels of atmospheric contamination and the use of air-side cooling within data centers require more attention towards air quality management as a data center encounters large variation of temperature, air flow and humidity over short distances. Besides temperature, humidity, and air flow, the concentration of gaseous contamination can also affect the corrosion rate in data centers. One concern of air side economization is the possibility of unintentional introduction in a facility of a large amount of gaseous and particulate pollutants potentially leading to more failures and outages of the IT equipment. That is, IT equipment operated at high temperatures and increased humidity combined with high level of air contamination can lead to enhanced corrosion risk in data centers.
Two types of contamination that have been identified to impose risk on IT equipment include particulates and gaseous contaminations. Recent investigation of the particulate contamination levels in data centers established that proper filtering can reduce the concentrations to acceptable levels. However, for gaseous contamination monitoring, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) publication [see, ASHRAE Whitepaper, “Gaseous and Particulate Contamination Guidelines for Data Centers”, 2009] states that reactivity should be measured both for copper and for silver. Currently, the study recommends that copper and silver corrosion rates should be maintained less than 300 Å/month for a non-contaminated environment. Furthermore the ASHRAE publication suggests that in situations where atmospheric contamination is high, proper filtration should be used to reduce the corrosion levels below 300 Å/month.
The ASHRAE guidelines are designed to minimize the physical failure risks of the IT equipment, while achieving higher energy efficiency. Certain limitations are set for temperature or relative humidity levels to reduce condensation or overheating risk of the IT equipment. For example, it is suggested that humidity levels below 20% can increase the probability of electrostatic discharge (ESD) and implicitly the failure of integrated circuit components. High humidity levels (above 70%) may increase the probability of Printed Circuit Board (PCB) delamination, anodic filament growth, zinc whisker growth and corrosion.
Standard industrial methods to measure corrosion rely on exposing metal (silver and copper) coupons to a polluted atmosphere and collecting the coupons after at least a one month period of such exposure. For field deployed copper and silver coupons, it has been observed that the corroded surface shows spatial variations across the surface depending on the direction of air flow, temperature, surface preparation and humidity. Even coupons which hang near each other will have different corrosion product thickness and variation across their surfaces indicating that the local environment has a large impact on the corrosion formation.
The desire of operating data centers (DCs) more energy efficient has resulted in two trends: (1) environmental operating parameters for IT equipment have been significantly expanded, and (2) air side economizers are increasingly used to offset cooling energy consumption, which can be substantial fraction of the total DC power. These two trends can have significant implications for the corrosion risk of a DC.
While filtering of the outside air, both for particulate and gaseous contamination, can mitigate air contamination in data centers, implementing a facility wide air quality monitoring system promises the safe use of air-side economizers and would establish appropriate filtering.